Individual differences in speech perception in noise: A neurocognitive genetic study

Abstract

Previous work has demonstrated that individual listeners vary substantially in their ability to recognize speech in noisy environments. However, little is known about the underlying sources of individual differences in speech perception in noise. Noise varies in the levels of energetic masking (EM) and informational masking (IM) imposed on target speech. Relative to EM, release from IM places greater demand on selective attention. A polymorphism in exon III of the DRD4 gene has been shown to influence selective attention. Here we investigated whether this polymorphism contributes to individual variation in speech recognition ability. We assessed sentence recognition performance across a range of maskers (1-, 2-, and 8-talker babble, and speech-spectrum noise) among 104 young, normal-hearing adults. We also measured their working memory capacity with Operation Span Task, which relies on selective attention to update and maintain items in memory while performing a secondary task. Results showed that the long variant of the DRD4 gene significantly associated with better recognition performance in 1-talker babble conditions only, and that this relation was mediated by enhanced working memory capacity. These findings suggest that the DRD4 polymorphism can explain some of the individual differences in speech recognition ability, but is specific to IM conditions.